The invention relates to an antibody-drug-conjugate (ADC) or conjugate and its use for the treatment of cancer.
ADCs combine the binding specificity of an antibody with the potency of drugs such as, for example, cytotoxic agents. The technology associated with the development of monoclonal antibodies, the use of more effective drugs and the design of chemical linkers to covalently bind these components, has progressed rapidly in recent years.
The use of ADCs allows the local delivery of drugs which, if administered as unconjugated drugs, may result in unacceptable levels of toxicity to normal cells.
In other words, maximal efficacy with minimal toxicity is sought thereby. Efforts to design and refine ADC have focused on the selectivity of antibody as well as drug mechanism of action, drug-linking, drug/antibody ratio (loading or DAR), and drug-releasing properties. Drug moieties may impart their cytotoxic and cytostatic effects by mechanisms including tubulin binding, DNA binding, proteasome, impairment of ribosome function, protein synthesis and/or topoisomerase inhibition. Some cytotoxic drugs tend to be inactive or less active when conjugated to large antibody.
Each antibody must be characterized separately, an appropriate linker designed, and a suitable cytotoxic agent identified that retains its potency upon delivery to tumor cells. One must consider the antigen density on the cancer target and whether normal tissues express the target antigen. Other considerations include whether the entire ADC is internalized upon binding the target; whether a cytostatic or cytotoxic drug is preferable when considering possible normal tissue exposure and/or the type and stage of the cancer being treated; and, whether the linker connecting the antibody to the drug payload is a cleavable or a non-cleavable linkage. Furthermore, the antibody to drug moiety conjugation ratio must be sufficient without compromising the binding activity of the antibody and/or the potency of the drug and without modifying physicochemical properties of the ADC resulting on aggregation or deleterious properties regarding to the future development process of the compound.
An ADC is a complex biological molecule and the challenges to develop an effective ADC remain a significant issue.